A data communication which is to be received by a device can be preceded by a pseudorandom noise (PN) sequence in a message. The PN sequence is included typically in a preamble of a frame, prior to the data payload included in the message.
To recover the transmitted message, a receiver must be synchronized to the received signal. Synchronization can be detected by checking the received PN sequence against a locally generated PN sequence.
If the received PN sequence in the data communication sufficiently checks against the locally generated PN sequence, then the receiver can assume that it is synchronized to the transmitter and can proceed to receive the rest of the data communication. Many existing protocols utilize a few well known and well understood generator polynomials in the PN sequences.
For proper operation, a locally generated PN sequence should be synchronized to the PN sequence of the transmitted signal. Knowledge of the data within the transmitted PN sequence allows the receiver to better train signal processing components that aid in the reception of the data message within the frame. Examples of such signal processing components are a decision feedback equalizer (DFE), a rake, a linear equalizer, or similar device having an equalization block. Known data sequences, such as PN sequences, that are transmitted and use to train processing blocks are often referred to as training sequences.
An equalizer typically retrains on the PN sequence for each received packet. This can allow the flexibility for the equalizer to adapt. However, some conventional equalizers do not retrain for each packet.